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CVE-2026-33168: Rails has a possible XSS vulnerability in its Action View tag helpers

• Severity: low (CVSS 2.3 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-03-23 · updated 2026-06-17
• Weakness: CWE-79

Description

Action View provides conventions and helpers for building web pages with the Rails framework. Prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1, when a blank string is used as an HTML attribute name in Action View tag helpers, the attribute escaping is bypassed, producing malformed HTML. A carefully crafted attribute value could then be misinterpreted by the browser as a separate attribute name, possibly leading to XSS. Applications that allow users to specify custom HTML attributes are affected. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.

Affected products

• Rubygems Actionview: from 8.1.0.beta1 before 8.1.2.1; from 8.0.0.beta1 before 8.0.4.1; before 7.2.3.1; 8.1.0, 8.1.0.beta1, 8.1.0.rc1, 8.1.1, 8.1.2, 8.0.0 (+295) — fixed in 8.1.2.1, 8.0.4.1, 7.2.3.1
• rails actionview: from 8.1.0.beta1, < 8.1.2.1; from 8.0.0.beta1, < 8.0.4.1; before 7.2.3.1

How to fix

Upgrade to a fixed version: Rubygems Actionview 8.1.2.1, 8.0.4.1, 7.2.3.1. Check the vendor advisory for mitigations.

References

• https://github.com/rails/rails/commit/0b6f8002b52b9c606fd6be9e7915d9f944cf539c
• https://github.com/rails/rails/commit/63f5ad83edaa0b976f82d46988d745426aa4a42d
• https://github.com/rails/rails/commit/c79a07df1e88738df8f68cb0ee759ad6128ca924
• https://github.com/rails/rails/releases/tag/v7.2.3.1
• https://github.com/rails/rails/releases/tag/v8.0.4.1
• https://github.com/rails/rails/releases/tag/v8.1.2.1
• https://github.com/rails/rails/security/advisories/GHSA-v55j-83pf-r9cq

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